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A. Kitamura, H. Iwai, R. Nishio, R. Satoh, A. Taniike and Y. Furuyama

In situ Accelerator-Based Characterization of CaO/Sr/Pd Samples under Deuterium Permeation. A. Kitamura, H. Iwai, R. Nishio, R. Satoh, A. Taniike and Y. Furuyama Department of Environmental Energy Science, Graduate School of Science and Technology, Kobe University

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A. Kitamura, H. Iwai, R. Nishio, R. Satoh, A. Taniike and Y. Furuyama

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  1. In situ Accelerator-Based Characterization of CaO/Sr/Pd Samples under Deuterium Permeation A. Kitamura, H. Iwai,R. Nishio,R. Satoh, A. Taniike and Y. Furuyama Department of Environmental Energy Science, Graduate School of Science and Technology, Kobe University 5-1-1 Fukaeminami-machi, Higashinada-ku, Kobe 658-0022, Japan E-mail : kitamura@maritime.kobe-u.ac.jp

  2. ・Deuterium permeation through Pd/(CaO+Pd)/Pd sample induced nuclear transmutations; 133Cs→141Pr, 88Sr→96Mo, 138Ba→150Sm and 137Ba→149Sm. 1. Y. Iwamura, M. Sakano and T. Itoh; Jpn. J. Appl. Phys. 41 (2002) 4642-4650. 2. Y. Iwamura, T. Itoh, M. Sakano, S. Kuribayashi, Y. Terada, T. Ishikawa and J. Kasagi; Proc. ICCF11, 2004, Marseilles, France. In the present work; ● The objective is ・ to investigate the dependenceof the transformation rate on material,D flux, flow direction, temperature, etc. ・ to find the optimum sample structure. ・ from a point of view of enhancing the transformation yield. ● Diagnostic methods; in situ and simultaneous measurements of compositional change during D permeation by accelerator analyses; PIXE (Particle induced X-ray emission analysis) RBS (Rutherford backscattering spectroscopy) NRA (Nuclear reaction analysis) ERDA (Elastic recoil detection analysis) as well as conventional XPS and Desorption measurements.

  3. Experimental procedure; in the present work, X =Sr, Y=CaO (1) Depositing X on Pd (A; the 1st stage); electroplating, (B; the 2nd stage); ion-beam sputtering deposition (1D) XPS for areal density of X (2) Forming a layer of Y on X/Pd (RF sputtering deposition) (2D) XPS for areal densities of Y andX (3D) In situ and simultaneous PIXE, RBS and NRA for areal densities of X,X’, (Y) and D distribution (done only for the sample B) (3) Permeation of D through Y/X/Pd causing nuclear transmutation XX’ (4) Desorption of D2 (4D) XPS for areal densities of Y,XandX’

  4. MCA Amp. Amp. Amp. Preamp. Preamp. D2 Recorder MCA MCA A Probe beam ionsfrom PELLETRON 5SDH2 0.8-2.5 MeV 3He++ for NRA 3 MeV pfor PIXE CaO/Sr/Pd Preamp. X-Ray Detector 1 atm D2gas RBS-SSD SSD for NRA with 4-mm Mylar filter Pressure gauge

  5. cf.; the sample used by Iwamura et al. Deuterium permeates through the CaO(10nm)/Sr/Pd sample from the rear surface out to vacuum. vacuum D2gas CaO/Sr/Pd 10nm / 0.1mm

  6. Recorder Sr atoms are deposited on one side of a 0.1-mm-thick Pd foil as contamination with an areal density of the order of 1014 cm-2. (1) Depositing Sr on Pd ; (A) electrochemical method 1 V A Pd Pt 10 mM Sr(NO3)2/D2O

  7. (1) Depositing Sr on Pd ; (B) ion beam sputtering Pd substrate Sr target Sr deposition rate; 1E13 atoms/cm2/s Sr 45° Ar+ ion beam Energy; 5 keV Current; ~2 A A Recorder

  8. (2) Forming a layer of CaO on Sr/Pd ; RF sputtering deposition RF sputtering condition • Cathode (sputter target); CaO • Anode (sample); Sr/Pd • Ar pressure; 0.1 Torr • RF power; 100 W • Plasma exposure time; 5 - 30 min. • Sample temperature; 450 K • CaO deposition rate; 0.1 - 0.5 nm/min

  9. Pd-3d Ca-2p Etching time (2D) XPS characterization after forming the layer of CaO on Sr/Pd Change in the sample structure is reflected in XPS spectra after repetitive etching of the CaO/Sr/Pd surface.

  10. The CaO layer thickness x is calculated from the intensity ratio of • these peaks, YCa-2p/YPd-3d; where , .

  11. The thickness of the CaO layer has been calculated from the XPS yield of the Pd-3d peak relative to that of Ca-2p to be about 10 nm for the sample #4. (2D) XPS characterization after forming the layer of CaO on Sr/Pd

  12. During D permeation, pressure in the reservoir has been monitored to calculate the number of absorbed/transmitted D atoms. (3) Permeation of D through CaO/Sr/Pd(the sample B) D flux (flow rate) 2.71015 cm-2s-1 (=0.02 sccm) D permeation toward a vacuum side PdD0.65

  13. Pd Pd(3He,3He) PdD0.86 PdD0.65 D(3He, 4He)p The NRA revealed the almost uniform composition of PdD0.65over the depth region of 0-1.8 m. (3D) NRA during permeation of D through CaO/Sr/Pd(the sample B) NRA using the D(3He, 4He)p reaction

  14. 7 10 Pd-K 6 10 before Fe-K initiation of D permeation 345 h after 5 10 586 h after Mo-K Pt-L 4 10 Sr-K Yield [counts/43 eV] 3 10 2 10 1 10 0 10 0 5 10 15 20 25 30 35 40 Energy [keV] The PIXE spectra revealed existence ofa variety of impurities. The Mo-Ka/b seems to be interfered by unidentified broad peaks. (3D) PIXE analysis during permeation of D through CaO/Sr/Pd(the sample B) ?

  15. Variation of the areal density of Sr during permeation of D for 590 hours. Results of ex-situ XPS are also plotted for comparison. (3D) PIXE analysis during permeation of D through CaO/Sr/Pd(the sample B)

  16. Outgassing of the sample after finishing D permeation was necessary for introduction into the XPS chamber. Total amount of desorbed D atoms measured with QMS indicates D/Pd0.3. (4) Desorption of D2

  17. The process of deuterium charging is described by a 1-dimensional • solution of the diffusion equation for the sample with a thickness • and area of a and S, respectively. • One side of the sample is assumed to be opaque for deuterium, • while the other facing to hydrogen gas to give a boundary condition • for the deuterium density; n(a) = n0. • The number of deuterium atoms absorbed in the sample, Na(t), • is given as a function of time by • A characteristic time t1/2 for the number of deuterium atoms absorbed • to reach a half of the saturation value, i.e., • Na(t1/2)/aS = Na()/2aS = 2.91022 cm-3, is therefore given by

  18. (4D) XPS characterization of the sample A after D2Desorption Sr-3d S-2s Mo-3d S-2p XPS spectra before and after D permeation. Increase in Mo-3d peaks in exchange for decrease in Sr-3d peaks is observed.

  19. XPS analysis implies nuclear transmutation near the CaO/Pd boundary:Sr atoms with areal density of 1.31014 cm-2 appear to be transformed to Mo atoms of 6.61013 cm-2by D permeation. (4D) XPS characterization of the sample A after D2Desorption

  20. An order of magnitude increase in areal density of Sr (2 monolayers) was realized by RF sputtering method. However, nuclear transmutation was not recognized for this sample. (4D) XPS characterization of the sample B after D2Desorption Sr-3d3/2 Mo-3d3/2 Sr-3d5/2 Mo-3d5/2 After D permeation Before D permeation

  21. Summary of changes in areal densities Sample A: Transmutation efficiency was 50%. Sample B: Decrease in areal density of Sr was not followed by consistent increase in other elements observable.

  22. Summary • Implication of nuclear transmutation SrMo has been obtained in a system [vacuum/CaO/Sr/PdDx/D2], which is a little simpler than that used by Iwamura et al. (2) The diagnostic method used to identify the elements was conventional XPS, giving the areal densities of 1.3 1014 cm-2 (Sr) and 6.61013 cm-2 (Mo). (3) Extended analytical methods have been prepared; in situ and simultaneous PIXE, RBS and NRA/ERDA for areal densities of transmutation elements and deuterium distribution. (4) Increase in the areal density of Sr to 3.31015 cm-2 by using ion beam sputtering method resulted in negligible transmutation yield.

  23. Summary (5) Further experimental work is necessary to confirm the phenomena; • Dependence on the density of the atoms to be transmuted, the areal density of the atoms, the flux (flow rate) of D, the sample structure, . • Effect of surface contamination.

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